terryl

My other "non-Oldsmobile" collector car is a '72 Malibu rag with a 307. It stripped the timing gears yesterday, and I had it towed to a local shop. They have come up with a price of $986.52 to replace the gears, including dropping and flushing the oil pan. Any possible engine damage will be over and above that figure.

A retired mechanic down the street says I am being bent over, and that I need to get it towed out of there before they do any more work to it. Does this figure appear excessive to anyone knowledgeable in this procedure?

TripDeuces

It's more than likely based on time x shop rate. With most shop rates hovering near the $100 or better per hour I'd say you're in the ballpark. It's inflation my friend. I personally think it's a bit expensive but then again I'd be doing it myself for that kind of money.

Highwayman

I inquired about having some work done on my truck at the GMC dealer last year. $130 an hour. I did it myself.

joe_padavano

He knows of what he speaks. LISTEN to the man. The timing set (chain and both gears) is $20 from RockAuto for a ROLLER chain (stock is even cheaper). The gasket set is $7. These are Cloyes and FelPro, not Chinesium parts, and that's RETAIL price.

I've NEVER had to drop and flush the oil pan when replacing a timing gear. The remains of the plastic teeth aren't going to hurt anything. DO replace the water pump when you have it off, however, or you'll be doing THAT shortly after fixing the timing chain. DO NOT ask me now I know this...

rocketraider

That's probably not bad money if they're going to drop the pan with engine in the car. Lot of stuff has to be moved and disconnected for that part of the job.

Timing chain itself is an easy job on a SBC, esp if no A/C or power steering. Pull the waterpump, remove the timing cover, wiggle it out and walla. There are the chain and gears in all their shredded glory. You might need a puller to get the crank gear off.

Worst part will be trying to get the cover back into the oil pan. Trimming a little off the inner lip of the oil pan front seal area makes it easier. Most later SBC covers have already had the inner lip trimmed back.

Since the pan has to come off to clean it out, might as well put in a new rear main seal while you're into it.

Highwayman

If you run a shop and stand behind your work, you do not leave things sloppy like debris in the pan.


Personally I don't like all that plastic crap stuck in the oil pump pickup screen because that's where it ends up, but that's me.

Allan R

I'm sorry, but where does all the plastic come from? I thought timing gears were made from metal...Where are the plastic teeth?

joe_padavano

Well, first of all, that plastic "crap" is not really chunks, it's plastic powder that's been worn off of the teeth over the last 100,000 miles or so. In reality, the powder is small enough to fit through the screen and was likely caught in the oil filter. I predict that you'll find nothing in the pan (other than the expected 100,000 miles of sludge). Your call, but pulling the pan is only a few bellhousing bolts away from pulling the whole engine, at which point I'd be looking for a rebuilt 307 long block - especially since rebuilt SBC long blocks can be had for well under $1,000.

Those MIGHTASWELLS will get you every time.

Sugar Bear

Talk to the tech about replacing the gears and chain, leaving the front cover off and doing a compression test before pulling the pan. If any valves are bent you may want think about going to a rebuild at that point. As the previous poster mentioned this can all add up in a hurry.

If the compression is good on all cylinders ask the shop if they have a borescope that they could look in the pan through the front cover to see if it really needs to be pulled and pull it only if chunks are laying in the pan.

As mentioned by a previous member if the water pump is old change it since you are already paying the labor. If the pan comes off a main bearing should be inspected for wear, it is only two more bolts to undo. Also check a rod bearing, I would check number five for condition. Why number five? Was taught this by a Chevrolet shop foreman and it was usually the one that would knock if over revved and it was number one, the farthest from the oil pump if it had an oiling problem.

jensenracing77

the original timing gear on the cam had a nylon outside. (to make them quieter i think). on average, you can expect to change them at 100,000 miles. the original gears on my dads 77 cutlass let go at over 250,000 miles. it completely disintegrated and had large chunks in the pan.we just drained the oil out and dried the pan the best we could with brake clean and then sucked the parts out with a vacuum and a small hose from the front when the timing cover was off.

Allan R

Thx Eric. That was the info that I was missing. Do replacement gears have the same issues?

jensenracing77

i don't think any aftermarket gears have the nylon. at least none that i know of.

Rickman48

I'd be bringing that shop a small tube of Vaseline, and suggest they give it to the next victim, so it doesn't hurt so much!![Obviously, after your car's outta there!]
Small block Chevy - 3hr job max, with parts and gaskets waiting!!!
Take a cold chisel to the lower gear at the keyway, and the fuel pump doesn't have to come out!!
Personally done around 40 - only 2 with bent valves, 1 with bent rod + broken piston!

At what RPM did it come apart, and quit running??
Just the facts!

terryl

Rickman, I was only cruising at about 35 mph. Heard a loud "buzzing" sound, for lack of a better word (I guess that noise was the plastic gears stripping), and realized the motor wasn't running anymore. Pulled over to the curb, tried to start it a couple of times, and figured by the sound that the timing was way off.

Great info on this thread, and I sincerely thank everyone for their suggestions. It seems that the main point of contention (and cost) is whether or not the pan has to be dropped and cleaned out.

This is the only website that I posed the question on, since I am a member, but on Googling "timing chain replacement", it seems that the general consensus is that the pan has to be dropped and cleaned out to prevent chunks of plastic timing gear being sucked up into the oil pump and creating oil flow blockage further down the road. The car has about 117K on it. I have had it for a dozen years, and while it had been restored in the past prior to me acquiring it, I don't know that any motor work had been done to it. It will produce a small puff of blue smoke when I first start it, but has always run fine and clean beyond that.

Terry

oldcutlass

#1 I don't believe an SBC has a plastic timing gear set. #2 it is about a 5 hr job and shold also include an oil change. There is also going to be a markup in parts. So based on current labor rates and parts costs, he's in the ballpark and covering his butt on what unforeseen issues may arise, for example an oil pan leak, current state of tune, on an older car.

Another thing to consider, is perhaps the mechanic is taking into consideration, that the car needs some extra TLC in putting it back together because its all clean and pretty in there and to get it to look the same when he is done will take extra time. Or perhaps he has other reasons to charge a bit more, based on previous dealings.

Capitalism, sometimes you get what you pay for!

If you feel his estimate is too high, by all means take it somewhere else. It's the price of not doing it yourself!

jensenracing77

Allan,
this is a picture of the nylon gear. this was pulled from a 330 engine with just over 100K miles. it is on the verge of complete disintegration. all the little black lines coming from the center aluminum part are cracks in the nylon. the teeth are not in bad shape but it would likely have fell apart in a few thousand more miles.

100_7698.jpg?t=1335129020

MDchanic

Here's another picture of a timing gear about to self-destruct:



- Eric

Allan R

Thanks guys, those pics are worth their weight in gold. I had no idea. So the 64K question: Are these the same for 70 and later 350's?

jensenracing77

i think most everything up into the early 90s?

bigD

yes unfortunately it is... they ran the nylon gears for a lot af years. this past winter i changed the timing set on my '70 350 that had 101k miles on it and it was insanely loose!! i'd say easily 2" of slop, teeth worn to points... and it was owned by an older couple that probably never flogged it and took meticulous care of it.

TripDeuces

My 70 had it and many were missing and broken. It did last 65k miles so I'm not complaining but they do break and wear away.

DeltaDevil88

On a Oldsmobile 307 V8 what is the suggested mileage for timing gear/chain service 100k?

joe_padavano

100k is pushing your luck. I usually replace original timing sets at 80K.

Allan R

I guess I must have been very lucky. My 83 Regency Brougham had over 190K on it when I sold it in 2003. It still had the original timing chain. Always started and ran strong for a 307 though.

J-(Chicago)

This may just be my first time in disagreement with Joe P.

Due to the design of the stock oil pump pickup, those chunks of plastic from the timing gear get sucked into the pickup and stay trapped there. Much like a lawnmower bag. I've never seen one completely obstructed before, but have seen a full bag of clippings
IMG_0339.jpg

J-(Chicago)

Plastic or no plastic, they should all come out every 80,000 miles. Even the 60's big block mopars with all steel gears start jumping time around 100k due to chain slack

Tony72Cutlass'S'

I was having this conversation with another fellow a couple weeks ago.

Apparently cloyes timing sets are just as easy as install and no need for degreeing your cam.

What tools are needed to perform the timing gear replacement? Realistically, i'll do my water pump at the same time.

MDchanic

• Regular wrenches
• A big air wrench (if engine off the car or radiator and condenser are out) -or-
• A big breaker bar (if engine is in the car)
• A big socket for the crank bolt (I think it's 1⅛", but I could be wrong...)
• Vibration damper puller
• Possibly a small gear puller (the crank gear sometimes sticks)

- Eric

Rickman48

I usually change the set when the water pump goes, 80-90k miles, or both at 90k.
More than that, and you're risking it!

A friends Dad asked me to do his water pump on a '78 Delta 350 - was very skeptical when I mentioned the chain + gears, and stood over me while I took it apart.
Was shocked to see 2 inches of play, and the condition of the upper gear!
Tipped me $50 for 'saving me a lot of money, to do it again'!
And I've never had a problem, leaving plastic parts in the pan! Any G.M.!
They usually come out with oil changes!

Tony72Cutlass'S'

My engine is definitely in the car, i only have a small 5 gallon compressor.. i guess i'll need to pick up a big breaker bar... How tight is the crank bolt usually?

Tony72Cutlass'S'

See.. my water pump was changed by the previous owner, BUT as you guys can see, he neglected so much on the car. I'm not sure if i'm ready to take the risk on the timing chain....

MDchanic

A couple of hundred foot pounds.

You'll probably need a pipe on the end of the breaker bar, or do it the old fashioned way: with the breaker bar firmly on the bolt, and resting on the ground on the driver's side of the car, blip the starter and it should loosen.

- Eric

Tony72Cutlass'S'

Wow that sounds like a great trick, should i be worried about the started stripping the flywheel with all that torque?

I'm going to see if i can rent a harmonic balancer pulled from my local store so i dont have to go out and buy one...

Tony72Cutlass'S'

Also i was just looking at the CSM, it seems there's an oil seal behind the harmonic balancer? I'm guessing that should be replaced?

MDchanic

Naah. The instantaneous torque on a high-compression 455 is pretty darn high when the starter starts, and the starter gear has about 8" of leverage advantage. If you're concerned you can remove the spark plugs, thus eliminating the added stress of compression.

Chain places like Advance ought to have 'em for "free rental."
Definitely no reason to buy one.

Might as well. Cheap and easy.

Tony72Cutlass'S'

Any idea what the p/N would be?? I can't seem to find Crankshaft balancer seal in rockauto anywhere

Cool, i'll loosen the plugs when i try that.

MDchanic

That's because it's called a Timing Cover Seal (2" shaft x 2.88" hole):
SKF #19887 -- $9.87
National #472082 -- $11.40

You will probably get a Timing Cover Gasket Set, though, which includes that seal:
FelPro #TCS45270 -- $12.50


- Eric

Tony72Cutlass'S'

Wow, that looks great! It's only 12 dollars for that whole set?

It's kinda odd, but the bottom black gasket looks like the edge of the oil pan gasket?

I always wanted to re-seal my oil pan, but i have an exhaust crossover right under the engine.....

MDchanic

Yup.

It is. The front of the oil pan seals against the timing cover.

I wouldn't go there, myself.
The oil pan is a minor, low-stress part, but I am petrified of breaking off exhaust manifold studs, and so avoid messing with them at all costs.

You might be able to get the pan down enough that you could degrease and re-seal the surfaces with silicone, with or without new gaskets, but I'd be cautious.

If you DO decide to drop the pan, I would recommend a small oxy-acetylene torch to heat the exhaust nuts dull red before trying to turn them.
Also, to drop the pan, you'll have to loosen the motor mounts and raise the engine.

- Eric

Tony72Cutlass'S'

Wow, Eric. That sounds like alot of work for a couple drips per day...

Maybe i could just re-torque the pan to factory spec? What's the best way? Criss cross from the inside out or outside in?

When i changed my starter last year, i noticed my oil pan bolts were almost finger tight....